非连续干湿循环对混凝土表层氯离子迁移的影响规律

Effects of Discontinuous Dry-Wet Cycles on Migration of Chloride in Concrete Cover

为探究滨海环境中干湿循环的不规律性对混凝土表层氯离子传输的影响,设计了连续、非连续干湿循环对比试验,研究了不同干湿循环下水灰比和干湿循环制度对混凝土表层氯离子含量分布规律及对流区氯离子含量变化规律的影响.结果表明:当自然风干时间/湿润时间(t_(d)/t_(w))较大时,由于双向对流与扩散的传输现象,使得氯离子含量在对流区存在1个拐点;对流区深度基本随水灰比减小而减小;连续干湿循环下氯离子峰值含量随着t_(d)/t_(w)的减小而增大;相较于连续干湿循环而言,非连续干湿循环对表层氯离子含量随深度的变化规律和氯离子峰值含量的影响较大.

In order to study the effect of the irregularity of dry-wet cycles on chloride transmission in concrete cover under marine environment, comparative tests under continuous and discontinuous dry-wet cycles were carried out.The effect of water-cement ratio and dry-wet cycles regime under different dry-wet cycles on the distribution of chloride content in concrete cover and the change of choloride content in convection zone was studied. The results show that the chloride content has an inflection point in the convection zone due to the transmission phenomenon of bidirectional convection and diffusion when the time of dry-wet ratio(t_(d)/t_(w)) is relatively high. The depth of convection zone decreases as the mass of water-cement ratio decreases, while the peak chloride content increases with the reduction of t_(d)/t_(w). Compared with continuous dry-wet cycles, the discontinuous dry-wet cycles have a significant effect on the variation of chloride content with the depth and the peak chloride content in the concrete cover.